For storing cigarettes, a store of the above type—as described, for example, in EP-0738478 or WO-9944446—is interposed between a cigarette manufacturing machine and a packing machine to compensate for any difference in the number of cigarettes produced and the number packed, by lengthening or shortening said first or conveying coil, and shortening or lengthening said second or return coil in complementary manner.
U.S. Pat. No. 5,361,888 discloses a reversible reservoir for cigarettes or filters including relatively small and relatively large capacity sections arranged in series with a drive for driving these sections at different rates. The small section is preferably arranged adjacent the reservoir inlet and is capable of buffering the main part of the reservoir so that the latter is not required to undergo high accelerations; the reservoir may be in the form of an elongated helix with an endless conveyor passing around spaced columns of wheels, one of the lowermost wheels being bodily movable so as to be capable of imposing an additional velocity on the section of conveyor adjacent the reservoir inlet. The movable wheel is carried on a which also carries a pulley for the conveyer return run; tensioning for the conveyor is provided by arranging for the position of the pulley to be adjustable relative to the beam.
FR2510527 discloses a feed for stocking articles between work positions; the feed is for stocking parts between two work positions and has an endless chain, along which are parts at even distances to hold the parts to be stocked. The chain has a vertical section of variable length; on this are loading supports for the stock, passing over a toothed wheel carried on a slide, which moves vertically and is permanently urged upwards. A second chain section is also of variable length and has unloaders for the stocked parts; a drive operates the chain upwards and another operates the chain downwards.
The conveyor of known stores of the above type is normally defined by a belt, the conveying surface of which is maintained, along the two coils, substantially parallel to itself and substantially on edge, i.e. perpendicular to the axes of the relative guide drums, and is transversely flexible to wind on edge about all the guide drums.
Consequently, known stores are relatively bulky by employing fairly large-radius guide drums along both the conveying and return branch, to prevent excessive tensile stress along the curved portions of the on-edge belt, and, at least as regards the conveying branch, instability of the conveyed mass of cigarettes due to excessively small radii of the curved portions.